System Design of Cavity Resonance-Enabled Wireless Power Transfer Based on Filter Design Theory

This study aims to realize an efficient system operation using wireless sensor networks (WSNs), which have been increasing in demand in recent years. To achieve this, a cavity resonance-enabled wireless power transfer (CR-WPT) technique has been proposed. The CR-WPT system is a WPT system that utilizes the cavity resonance phenomenon inside the cavity. This study solves the impedance mismatch problem caused by the resonance frequency changes depending on the installation condition of objects in the cavity resonator, which results in a power transmission efficiency(PTE) decrease. We propose the implementation of J-inverters and additional resonators outside and inside the cavity resonator and the configuration of a three-stage band-pass filter(BPF) to achieve broadband matching. The EM analysis results show that adding the J-inverters and additional resonators produces three poles in the reflection characteristics, verifying the proposed system operates as a three-stage BPF. A broadwidth of the power-supply frequency is realized. With a 2 W power input in the 117–122 MHz band, the bandwidth was broadened from approximately 0.6 to 2.0 MHz, which is approximately thrice the bandwidth of the previous system.